Surface texturing to increase lateral coefficient of friction

ABSTRACT

A seal for an annular space includes a mandrel; and an element having a surface treatment to increase the coefficient of friction thereof at least on a surface of the element configured to interact with the mandrel. A material for use as an element to seal an annular space, the material including a surface treatment to increase lateral coefficient of friction. A method for producing a seal for an annular space.

BACKGROUND

In many industries, elements that are intended to extend from a central mandrel and interact with an opposing surface are used for holding a differential pressure across the element. These elements need to be maintained in position in order to be effective. Unfortunately, differential pressures tend to extrude a portion of the element or swab the entire element. Extrusion or swabbing of an element is obviously problematic since where such occurs, the point of the structure, which was to hold a differential pressure, may be reduced or lost. These conditions also may result in a reduction in lifespan of the element. In any case, cost is most certainly increased and other detrimental effects may be incurred. Sometimes, extrusion is addressed with anti-extrusion devices disposed at either end of the element but these are expensive, cumbersome, extend overall length of a seal making tool, etc.

In all industries, expenses need to be minimized while effective constructions are produced. In view hereof, relevant arts are always receptive to new developments and configurations that promote product reliability and function.

BRIEF DESCRIPTION

A seal for an annular space includes a mandrel; and an element having a surface treatment to increase the coefficient of friction thereof at least on a surface of the element configured to interact with the mandrel.

A material for use as an element to seal an annular space, the material including a surface treatment to increase lateral coefficient of friction.

A method for producing a seal for an annular space includes surface treating a material configured to act as an element; adhesively attaching the element to a mandrel incorporating at least some of the surface treatment into an interface between the element and the mandrel.

BRIEF DESCRIPTION OF THE DRAWINGS

The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike:

FIG. 1 is a schematic cross section view of a workpiece prior to patterning;

FIG. 2 is a schematic cross section view of the workpiece after micropatterning;

FIG. 3 is a schematic cross section view of the workpiece after nanotexturing; and

FIG. 4 is a schematic cross section view of a packer configured according to this disclosure.

DETAILED DESCRIPTION

A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures.

In connection with the disclosure hereof, it has been determined that applying surface treatments that increase the coefficient of friction of an element of a seal for an annular space that in some embodiments may be a downhole seal such as a packer, has the beneficial effect of increasing the resistance of the element to swabbing and extruding. Those of skill in the art will understand swabbing to be the sliding of a seal on a mandrel to which the seal is supposed to be attached and immovable. Those of skill in the art will understand extrusion to be the forcing of a portion of an element of a seal out of position due to pressure differential across the seal. Extrusion of an element may result in failure of the element to hold pressure if the degree of extrusion is sufficient.

Referring to FIG. 1, a schematic representation of a workpiece material 10 is illustrated. This illustration is merely to illustrate the effects of the surface treatment that is applied to the material to arrive at the end configuration being disclosed. The material 10 may comprise polymeric material such as polydimethyl siloxane and/or perfluouro elastomers or other materials such as nitrile butadiene rubber (NBR), hydrogenated nitrile butadiene rubber (HNBR), tetrafluoroethylene and propylene rubber (FEPM), and fluoroelastomer (FKM). In an embodiment the workpiece is an element for a packer or similar seal often used in the downhole industry for holding annular differential pressure.

Referring to FIG. 2, the material 10 is illustrated after a patterning operation. The patterning operation may be selected from but is not limited to micro-molding, micro- patterning, micro-embossing, chemical etching, laser etching and reactive ion etching, for example. As illustrated in FIG. 2, the patterning is a micro-post pattern where measurements for a, b, and c are in ranges of 10 μm to 500 μm, 0.1 μm to 50 μm and 1 μm to 100 μm, respectively. The material 10 can be viewed as a finished product at this point or may be further processed as discussed relative to FIG. 3.

Referring to FIG. 3, the patterned material 10 is textured. Texturing in some embodiments is microtexturing or nanotexturing. It is to be understood that while the texturing illustrated in FIG. 3 is an additional surface treatment on the already patterned material 10, the texturing could be used independently of the patterning on the material 10, i.e. texturing only with no patterning. All end results of 1) patterned alone 2) patterned and textured, and 3) textured alone are contemplated herein. It is also to be understood that different areas of the same material 10 may be different ones of the possibilities listed above.

In each case, the patterning and/or texturing provides for an increase in the lateral coefficient of friction between the material 10 and a contact surface against which the material 10 is intended to bear. For example, contact surfaces for the material when configured as an element are, referring to FIG. 4, the mandrel 14, the backups 16 and the inside surface 18 of a tubular in which the element is to be set. The patterning and/or texturing does not increase an independent adhesive characteristic of the material in a direction normal to the surface against which it is intended to bear but it does increase the ability for adhesive applied to that surface to hold there. This is particularly important when considering the surface of the material intended to be adhesively joined to a mandrel in the case of a packer using an adhesive or vulcanization. In areas where adhesive is not employed, the fact that the patterning and/or texturing does not increase hold in a direction normal to the surface allows for removal of the material 10 from the surface with no greater effort than would be required for removal of the material 10 prior to being patterned and/or textured. This is helpful in the instance of a resettable packer that is set and unset to be moved. Accordingly, the material 10 will tenaciously hold its position when in contact with a surface in the face of differential pressure across material 10 or other force thereon that would otherwise tend to move the material 10 laterally on the opposing contact surface, yet material 10 will easily lift off of the opposing contact surface as if no patterning or texturing had been applied.

The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Further, it should further be noted that the terms “first,” “second,” and the like herein do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. The modifier “about” used in connection with a quantity is inclusive of the stated value and has the meaning dictated by the context (e.g., it includes the degree of error associated with measurement of the particular quantity).

The teachings of the present disclosure may be used in a variety of well operations. These operations may involve using one or more treatment agents to treat a formation, the fluids resident in a formation, a wellbore, and/or equipment in the wellbore, such as production tubing. The treatment agents may be in the form of liquids, gases, solids, semi-solids, and mixtures thereof Illustrative treatment agents include, but are not limited to, fracturing fluids, acids, steam, water, brine, anti-corrosion agents, cement, permeability modifiers, drilling muds, emulsifiers, demulsifiers, tracers, flow improvers etc. Illustrative well operations include, but are not limited to, hydraulic fracturing, stimulation, tracer injection, cleaning, acidizing, steam injection, water flooding, cementing, etc.

While the invention has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the claims. Also, in the drawings and the description, there have been disclosed exemplary embodiments of the invention and, although specific terms may have been employed, they are unless otherwise stated used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention therefore not being so limited. 

What is claimed is:
 1. A seal for an annular space comprising: a mandrel; and an element having a surface treatment to increase the coefficient of friction thereof at least on a surface of the element configured to interact with the mandrel.
 2. The seal as claimed in claim 1 further comprising an adhesive between the element and the mandrel.
 3. The seal as claimed in claim 1 further comprising the surface treatment on a surface of the element configured to interact with one or more backups of the seal.
 4. The seal as claimed in claim 1 further comprising the surface treatment on a surface of the element configured to interact with an opposing structure against which the seal is intended to create a seal.
 5. A material for use as an element to seal an annular space, the material including a surface treatment to increase lateral coefficient of friction.
 6. The material as claimed in claim 5 wherein the surface treatment is a patterning.
 7. The material as claimed in claim 5 wherein the surface treatment is a micro texturing.
 8. The material as claimed in claim 5 wherein the surface treatment is a nanotexturing.
 9. The material as claimed in claim 5 wherein the surface treatment is a patterning and one or both of a micro texturing and a nanotexturing.
 10. A method for reducing swabbing of an element comprising surface treating the element to increase a lateral coefficient of friction with a mandrel upon which the element is mounted.
 11. A method for producing a seal for an annular space comprising: surface treating a material configured to act as an element; adhesively attaching the element to a mandrel incorporating at least some of the surface treatment into an interface between the element and the mandrel.
 12. The method as claimed in claim 11 wherein the surface treatment is disposed to interact with at least one backup of the seal for an annular space.
 13. The method as claimed in claim 11 wherein the surface treatment is disposed to interact with a surface against which the element is intended to seal during use. 